In late years, in application to optical materials such as mircolenses for digital camera modules, imaging lenses, optical elements (mircolens arrays, optical waveguides, optical switching, Fresnel zone plates, binary optical elements, blazed diffraction optical elements and photonic crystals); application to semiconductor manufacturing process materials such as resist materials for ArF excimer laser exposure or EUV exposure; and application to electronic device materials such as anti-reflection filters, recording media, display materials, organic ELs, liquid crystal plastic materials and the like, there has been increasingly demanded a highly transparent resin material having high purity and there has been reviewed the development of wide application of a cyclic olefin polymer having excellent optical properties in the above fields.
As a method for producing a cyclic olefin polymer, there has been known a method for polymerizing a cyclic olefin monomer using a coordination polymerization catalyst, an addition polymerization catalyst, a living radical polymerization catalyst or a ring-opening metathesis polymerization catalyst and a hydrogenation reaction catalyst (catalyst for use in hydrogen addition (hereinafter referred to as hydrogenation) of double bonds remained after the ring-opening metathesis polymerization).
A metal component contained in the catalyst remains in the cyclic olefin polymer, whereby the metal component causes the change of color in a polymer material and a product, deterioration of optical properties, adverse effect on electrical and electronic properties, contamination of metals in a semiconductor manufacturing process and the like. Thus, an object is to avoid these problems for the development of a cyclic olefin polymer for use in the most advanced technologies.
To solve these problems, there has been proposed a method of removing the residual metal component from the polymer from the past. As a method of removing the residual metal in a cyclic olefin polymer product to be manufactured by the use of a transition metal catalyst, there have been known, for example, a method of bringing a solution of a coordination copolymer of a cyclic olefin monomer and olefin into contact with an aqueous alkali solution or an aqueous acid solution, or a method of bringing a solution of a coordination copolymer of a cyclic olefin monomer and olefin into contact with a filter material such as diatomaceous earth (Patent Document 1), and a method of lowering palladium of 6.0 ppm down to 0.13 ppm relative to the unit mass in the polymer by treating a cyclic olefin polymer obtained by subjecting a cyclic olefin monomer to addition polymerization using a palladium catalyst with an absorbent modified with mercaptopropyltrimethoxysilane on a silica surface (Patent Document 2).
Meanwhile, as a method for purifying a polymer obtained by a ring-opening metathesis polymerization reaction and a hydrogenation reaction, there has been known a method for obtaining a hydrogenated thermoplastic norbornene polymer having the content of metals such as titanium derived from a polymerization catalyst of equal to or less than 1 ppm by treating a polymer solution containing a polymerization catalyst residue with a hydrogenation catalyst-supported adsorbent (Patent Document 3).
Patent Document 4 discloses the following method.
A hydrogenated ring-opening metathesis polymer solution is obtained by subjecting a cyclic olefin monomer containing ester to ring-opening metathesis polymerization using a tungsten catalyst, and then carrying out a hydrogenation reaction using a ruthenium complex catalyst. Thereafter, an oxidant or a basic compound is added to the hydrogenated ring-opening metathesis polymer solution, and an operation to extract the residual metal component is repeatedly carried out to remove the metal component in a poor solvent phase. Then, tungsten in the polymer is reduced to less than 3 ppm and ruthenium is reduced to less than 0.1 ppm.
Furthermore, Patent Document 5 discloses the following method.
A cyclic olefin monomer having a cyano group is subjected to ring-opening metathesis polymerization using a molybdenum catalyst. Thereafter, trimethylenediamine is added thereto, and a polymer solution is added to methanol with stirring to precipitate a ring-opening metathesis polymer. Furthermore, the ring-opening metathesis polymer is brought into contact with an acidic compound and then the metal component is reduced to 30 ppm from 430 ppm by being discharging into methanol.
Patent Document 6 discloses the following method.
3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride is subjected to ring-opening metathesis polymerization with bis(tricyclohexylphosphine)benzylideneruthenium chloride, that is, a ring-opening metathesis catalyst, and inactivated with vinyl acetate after completion of polymerization. Therefore, a cyclic olefin polymer containing an oxygen atom in the main chain of the polymer is obtained. A solution containing the polymer is adsorbed by passing through activated alumina three times, whereby the polymer is purified by removing the transition metal derived from the polymerization catalyst.